The present invention relates to droplet deposition apparatus, in particular an inkjet printhead.
FIG. 1 shows an inkjet printhead of the kind disclosed in WO91/17051 and made up of a body formed with an array of open-topped channels which are closed by a cover. Each channel is connected at either end to a respective ink supply chamber and at its middle to a nozzle formed in the cover. The channel walls comprise piezoelectric material that deflects when subjected to an electric field and causes the ejection of an ink droplet from the respective nozzle.
Preferred forms of the present invention have as an objective a device of the kind described above which is simple and cheap to manufacture.
In one aspect the invention comprises droplet deposition apparatus comprising: a body formed with at least one channel open on one side, the channel communicating at each end with a supply chamber for supply of droplet fluid, actuator means being associated with each channel for effecting ejection of droplets; a cover closing the open side of the at least one channel and having formed therein at least one opening for ejection of droplets from the channel; and a base defining with the cover the supply chambers communicating with the respective ends of the at least one channel.
In such a construction, ink supply chambers that are defined by the base and cover require less critical tolerances than when they are formed in the xe2x80x9cactivexe2x80x9d body, as in WO91/17051. Furthermore, the base can be made of a material that is less expensive than that from which the bodyxe2x80x94the xe2x80x9cactivexe2x80x9d component in the printheadxe2x80x94is formed.
A second aspect of the invention involves the control means of inkjet printheads and comprises droplet deposition apparatus comprising: a body formed with at least one chamber open on one side, each chamber communicating with an opening for ejection of droplets therefrom and with a manifold for supply of droplet fluid, actuator means being associated with each chamber for effecting ejection of droplets in response to electrical signals and a cover closing the open side of the at least one chamber; the manifold being defined at least in part by a base, the base also defining at least in part a further chamber, control means for supplying the electrical signals to the actuator means being located in the further chamber.
In this fashion, the control meansxe2x80x94generally an integrated circuitxe2x80x94is itself integrated into the printhead construction, thereby increasing compactness and reducing the exposure of the integrated circuit to the environment.
In a third aspect, the present invention consists in droplet deposition apparatus comprising first and second channels, one end of each channel communicating with a single, common supply chamber for supply of droplet liquid and the respective other ends of the first and second channels each communicating with a respective further supply chamber for supply of droplet liquid; each of said first and second channels having an opening for ejection of droplets therefrom; and actuator means being associated with each channel for effecting the ejection of droplets.
Such an arrangement results in a compact construction in which droplet fluid can be passed from the single, common liquid supply chamber, through each of the first and second channels, and out into the respective further liquid supply chamber. Flow can also take place in the reverse direction. Such circulation can serve a number of purposes that are known per se, e.g. removal of dirt and air bubbles, cooling of the channel.
According to a fourth aspect, the invention consists in droplet deposition apparatus comprising a body formed with at least one chamber having an open side, each chamber communicating with a supply of droplet fluid and an opening for ejection of droplets therefrom; actuator means being associated with each chamber for effecting ejection of droplets in response to electrical signals, a support member for said body, the support member closing the open side of said chamber and having at least one track thereon for conveying electrical signals to respective actuator means, and having formed therein at least one opening for ejection of droplets from respective chambers.
This configuration has been found to be particularly suited to manufacture: the support member is not merely a support during manufacture for the active body componentsxe2x80x94and, advantageously, drive chips mounted on the conductive tracks it also provides location for each nozzle associated with each chamber in the bodies. An associated method is also comprised within the present invention.
A fifth aspect of the invention relates to a substrate having electrically conductive tracks, there being a plurality of locations along each track at which an integrated circuit may be connected; the plurality of locations being spaced relative to one another along each track such that, for each track, a location lying adjacent a connection to an integrated circuit die falls outside the footprint of the integrated circuit die.
In the event of a mounted integrated circuitxe2x80x94particularly a printhead drive chipxe2x80x94proving faulty, this measure allows a replacement chip to be connected to tracks on a substrate without having to remove the faulty chip, with the potential damage to the substrate that removal implies. Manufacturing yield benefits correspondingly. An associated method is also comprised within the present invention.